What you should know about Deltakron
3/24/2022 8:34 AM
As pathogenic as Delta, and as infectious as Omicron – the specter of this super-coronavirus has been haunting for some time. In this context, the catchy but unofficial name Deltakron sometimes appears. At the beginning of the year, researchers from Cyprus initially wanted to demonstrate a mixture of two Sars-CoV-2 Delta and Omicron variants. It soon became clear that it was most likely an error due to contamination in the lab. In the meantime, however, reports of Deltakron cases are piling up again. Questions and answers about this:
What does the World Health Organization say?
The World Health Organization (WHO) monitors a so-called recombinant consisting of one subtype each of delta (AY.4) and omicron (BA.1). The technical abbreviation for this is XD. The first samples come from France and are from January. For Germany, the Robert Koch Institute (RKI) reports a confirmed case on demand and refers to other descriptions in France, Denmark and the Netherlands.
The World Health Organization said there were no indications of a good spread so far. Monitoring by the World Health Organization does not mean that XD is classified as a concern or interest. As a result, it has not yet been given its name. The term Deltakron, which is sometimes popular in the media, is not explicitly used by the World Health Organization.
What speaks against the name Deltakron?
For experts, the term is not very accurate and is suitable only for clarity. Because recently it has been used not just for XD, but for different mixed forms of Delta and Omicron. “It is not a useful term, because it is unclear what the recombinant is intended and the term conveys an alarm for which there is no good reason,” said Richard, head of the Evolution of Viruses and Bacteria research group at the university’s Biozentrum. From Basel closer.
British virologist Tom Peacock recently explained on Twitter that the hybrid XD device discovered in France is different from that described in the UK, called the XF. Neher explained that XD is the only variant in which the omicron spike protein is “more or less perfectly” inserted into the delta genome. The virus enters human cells with spike protein.
How do such mixed forms arise?
This phenomenon is by no means surprising. “Such Sars-CoV-2 recombinants were expected. This can always happen when two different species are circulating at the same time: for example, if a person has a delta and an omicron at the same time,” said virologist Friedman Weber ( University of Justus-Liebig-Giessen) The infected host cell can exchange viral genetic material. But this is considered relatively rare. According to experts, in addition to the mixed forms of delta and omicron, subtypes of omicron BA.1 and BA.2 also appeared.
The current evidence also has to do with the fact that the virus has changed more and more with the increase in the number of infections. In variants that are genetically very similar from the first stage of the epidemic, recombination has been difficult to detect, French researchers wrote in a preprint of cases in southern France.
Does mixed diversity threaten to make the epidemic worse?
“It would be a mistake to assume that such recombinants are necessarily horrific variants that combine the worst properties of the original variants,” Weber said. Omicron subtype BA.2, currently prevalent in Germany, is almost as contagious as measles – the virus cannot grow much more. “Although Omicron is often associated with a milder course of the disease, it remains to be seen to what extent this also applies to unvaccinated older adults.” Virologist Peacock wrote that of the combinations seen so far, only XD is perhaps more worrisome. If any of these hybrid variants should behave differently than the original variants, it might be XD.
What to do now?
Virologist Christian Drosten summed up in an interview with Zeit: “In some cases, these re-associations have only occurred in limited outbreaks. Others seem to be increasing linearly at the moment, but fortunately this is not done significantly yet. It should be noted. And take this very seriously.” On Wednesday the situation together. Weber also advises more monitoring – and mentions that some variants have already emerged in the epidemic, which he hasn’t heard about since again. “These recombinants could once again disappear into the mists of history.”
How well is it to monitor variables given the current large number of cases?
In Germany, a full genetic analysis is performed and paid for by laboratories only for a very small percentage of all positive results. Virologist Sandra Ciesek of the University Hospital in Frankfurt said labs, at full capacity, had sequenced less than five percent of samples for capacity reasons. Rare virus variants will only be discovered by chance. It also regrets the omission of variant-specific PCR with the recently modified test list: the procedure can be used to detect abnormalities, which have already led to the detection of some rare virus variants.